This invention relates in general to devices for comminuting scrap material, and in particular to the rotor knives for such a device.
In U.S. Pat. No. 4,161,296 a granulator for comminuting scrap materials is shown. The scrap material is cut into particles by a set of rotor knives that rotate past stationary bed knives. The rotor knives are parallel flat blades secured together in a cylindrical array. A perforated screen below the rotor knives allows the scrap material to pass through for collection after it has been cut to a desired size.
One difficulty with this type of granulator is that the granulator requires a large electric motor to rotate the rotor knives. To conserve energy, it would be desirable to reduce the power requirement. Another problem occurs when the blades are resharpened. As the forward edge is ground back, the space between the rotor blades and bed knives, and the rotor blades and perforated screen increase. This reduces the efficiency of the device.
In U.S. Pat. No. 3,845,907, a device for comminuting trash is shown. This device differs from granulators in that it uses two rotating axles spaced-apart from each other. Disk-shaped blades, mounted to each axle, intermesh with each other to shred the trash. Two types of disks are shown in FIG. 7 and 9. In the type shown in FIG. 9, three cutting tongues are spaced at the periphery of the disks for shredding the trash. The device of U.S. Pat. No. 3,845,907 does not have provisions for passing particles through apertures in a perforated screen to assure a minimum size for collection and further use. Also, the device of this patent does not have stationary bed knives.